This document describes a robot that can be controlled via DTMF tones sent from a mobile phone. The robot has a mobile phone attached that can receive DTMF tones corresponding to buttons pressed on the calling phone. A microcontroller on the robot decodes the tones and controls motors via an H-bridge motor driver to move the robot in different directions. The system allows remote robotic control over large areas using existing mobile networks without interference from other controllers.

1. ABSTRACT
In this project, we present the controlling of a Robot using DTMF technique .The robot is
controlled by a mobile phone that calls the other mobile phone attached to the robot. In the
course of the call, if any button is pressed, the tone corresponding to the button pressed is heard
at the other end. This tone is called “Dual Tone Multi Frequency tone (DTMF)”.Using DTMF
code, direction of motion of the robot can be controlled by mobile phone. The above system can
be used for military purpose as ‘bomb detector’ and as ‘spy robot’ and also for surveillance.
DTMF Mobile ROBO is a machine that can be controlled with a mobile . In this project, the
robot is controlled by a mobile phone that makes a call to the mobile phone attached to the robot.
In the course of a call, if any button is pressed, a tone corresponding to the button pressed is
heard at the other end of the call. This tone is called "Dual Tone Multiple-Frequency" DTMF)
tone. The robot perceives this DTMF tone with the help of the phone stacked on the robot.
The received tone is processed by the microcontroller with the help of DTMF decoder. The
microcontroller then transmits the signal to the motor driver ICs to operate the motors & our
robot starts moving Conventionally, Wireless-controlled robots use rf circuits, which have the
drawbacks of limited working range, limited frequency range and the limited control. Use of a
mobile phone for robotic control can overcome these limitations. It provides the advantage of
robust control, working range as large as the coverage area of the service provider, no
interference with other controllers and up to twelve controls.
Although the appearance and the capabilities of robots vary vastly, all robots share the feature of
a mechanical, movable structure under some form of control. The Control of robot involves three
distinct phases: perception, processing and action. Generally, the preceptors are sensors mounted
on the robot , processing is done by the on-board microcontroller or processor, and the task is
performed using motors or with some other actuators.
1

2. 2
Chapter 1
INTRODUCTION
In this project, we present the controlling of a Robot using DTMF technique .The robot is
controlled by a mobile phone that calls the other mobile phone attached to the robot. In the course
of the call, if any button is pressed, the tone corresponding to the button pressed is heard at the
other end. This tone is called “Dual Tone Multi Frequency tone (DTMF)”.Using DTMF code,
direction of motion of the robot can be controlled by mobile phone. The above system can be used
for military purpose as ‘bomb detector’ and as ‘spy robot’ and also for surveillance.
1.1 Keywords:
Mobile phones, DTMF decoder, controller.
This is the block diagram of controlling robot using DTMF.
Fig.-1.1 Show the block diagram of controlling robot using DTMF.
1.2 DTMF TONE:
The DTMF technique outputs distinct representation of 16 common alphanumeric
characters (0-9, A-D, *, #) on the telephone. The lowest frequency used is 697Hz and the highest

3. frequency used is 1633Hz. The mobile that makes a call to the mobile phone stacked in the robot
acts as a remote. So this simple robotic project does not require the construction of receiver and
transmitter units. DTMF signaling is used for telephone signaling over the line in the voice
frequency band to the call switching center. The version of DTMF used for telephone dialing is
known as touch tone.
DTMF assigns a specific frequency (consisting of two separate tones) to each key s that it can
easily be identified by the electronic circuit. The signal generated by the DTMF encoder is the
direct algebraic submission, in real time of the amplitudes of two sine (cosine) waves of different
frequencies, i.e., pressing 5 will send a tone made by adding 1336 Hz and 770 Hz to the other
end of the mobile.
Fig.-1.2 Dual Tone Multi Frequency (DTMF) Frequency Standards
3

4. The DTMF keypad is arranged such that each row will have its own unique tone frequency and
also each column will have its own unique tone frequency. Above is a representation of the
typical DTWMF keypad and the associated row/column frequencies. By pressing a key, for
example 5, will generate a dual tone consisting of 770 Hz for the low group and 1336 Hz for the
high group.
All types of the mt8870 series use digital counting techniques to detect and decode all the sixteen
DTMF tone pairs in to a four bit code output. The built -in dial tone rejection circuit eliminated
the need for pre- filtering. When the input signal given at pin2 (IN-) single ended input
configuration is recognized to be effective, the correct four bit decode signal of the DTMF tone
is transferred to Q1 (pin11) through Q4(pin14) outputs.
4
1.3 DTMF DECODER:
Fig.-1.3 Show the pin diagram DTMF DECODER

5. 5
Chapter 2
HOW IT WORKS
2.1 TEST CIRCUIT:
Fig.-2.1 Show the TEST CIRCUIT
Following are the outputs produced by the DTMF decoder when the respective keys are pressed:

6. Table.-2.1 outputs produced by the DTMF decoder
6
2.2 MICRO CONTROLLER:
Micro controller is a programmable logical devise which can be used to control robots or any
appilicance. Here we use ATMEGA-16 micro controller in our circuit to control the robot .At
mega 16 is a 40 pin Ic which is easily available in the market. The following diagram gives the
pin description of the micro controller.
When we have to learn about a new computer we have to familiarize about the machine
capability we are using, and we can do it by studying the internal hardware design (devices
architecture), and also to know about the size, number and the size of the registers. A
microcontroller is a single chip that contains the processor (the CPU), non-volatile memory for
the program (ROM or flash), volatile memory for input and output (RAM), a clock and an I/O
control unit. Also called a "computer on a chip," billions of microcontroller units (MCUs) are
embedded each year in a myriad of products from toys to appliances to automobiles. For
example, a single vehicle can use 70 or more microcontrollers. The following picture describes a
general block diagram of microcontroller.

7. Fig.-2.2 Pin diagram ATMEGA-16 micro controller in our circuit to control the robot
Program required to control the robot is written and burnt into this controller and when the
required input gets into the controller it produces the desired output as per our logic written in
the program it is to be noted that each and every motor has two terminals one of them represents
positive terminal and other represents negative. Taking this point into account the logic is formed
in the following way.
7

8. The following table gives you the logic to drive the dc motors.
Table-2.2 The following table gives you the logic to drive the dc motors.
8
1=5 v
0= Gnd
The output from this micro controller is taken and given to a motor driver circuit which will
amplify the incoming signal to the required level we use l293d Ic as motor driver. The
Fig.-2.3 Controll DC motors with an H-Bridge IC
Mobile phone is connected to ear phones and the earphones are dissected in the following way

9. Fig.-2.4 Mobile phone is connected to ear phones
9
Following is the circuit diagram.
Fig.-2.5 Show the different IC in Robot System

10. 10
2.3 Components used in this circuit:
 Decoder
 Microcontroller
 H-bridge
 Crystal Oscillator
 Resistors
 Capacitors
 Diodes
 Power supply
2.4 Software Used:
 Professional Proteus
 Win Avr
 Avr studio
 Extreme burner
2.5 Advantages:
 Used to control house hold appliances
 In industries and factories for remote sensing
 Using 3g technology we can spy a place
 Long distance remote sensing
 Can be implemented in avionics to switch auto pilot from ground station by sending a
particular frequency

11. 11
Chapter 3
A BRIEF INTRODUCTION TO 8051 MICROCONTROLLER
3.1 8051 MICROCONTROLLER
When we have to learn about a new computer we have to familiarize about the machine
capability we are using, and we can do it by studying the internal hardware design (devices
architecture), and also to know about the size, number and the size of the registers.
A microcontroller is a single chip that contains the processor (the CPU), non-volatile memory for
the program (ROM or flash), volatile memory for input and output (RAM), a clock and an I/O
control unit. Also called a "computer on a chip," billions of microcontroller units (MCUs) are
embedded each year in a myriad of products from toys to appliances to automobiles. For
example, a single vehicle can use 70 or more microcontrollers.
The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of
in-system programmable Flash memory. The device is manufactured using Atmel’s high-density
nonvolatile memory technology and is compatible with the industry-standard 80C51 instruction
set and pin out. The on-chip Flash allows the program memory to be reprogrammed in-system or
by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with in-system
programmable Flash on a monolithic chip, the Atmel AT89S52 is a powerful
microcontroller, which provides a highly flexible and cost-effective solution to many, embedded
control applications.
The AT89S52 provides the following standard features: 8K bytes of Flash, 256 bytes of RAM,
32 I/O lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-vector two-level
interrupt architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In
addition, the AT89S52 is designed with static logic for operation down to zero frequency and
supports two software selectable power saving modes. The Idle Mode stops the CPU while
allowing the RAM, timer/counters, serial port, and interrupt system to continue functioning. The
Power-down mode saves the RAM con-tents but freezes the oscillator, disabling all other chip
functions until the next interrupt.

12. Fig.-3.1 An entire computer on single chip
12

13. The hardware is driven by a set of program instructions, or software. Once familiar with
hardware and software, the user can then apply the microcontroller to the problems easily.
The pin diagram of the 8051 shows all of the input/output pins unique to microcontrollers:
Fig.-3.2 pin diagram of the 8051
The following are some of the capabilities of 8051 microcontroller.
13
1. Internal ROM and RAM
2. I/O ports with programmable pins
3. Timers and counters
4. Serial data communication

14. 14
Chapter 4
HARDWARE DESCRIPTION:
4.1 POWER SUPPLY:
Power supply is a reference to a source of electrical power. A device or system that supplies
electrical or other types of energy to an output load or group of loads is called a power supply
unit or PSU. The term is most commonly applied to electrical energy supplies, less often to
mechanical ones, and rarely to others. Here in our application we need a 5v DC power supply for
all electronics involved in the project. This requires step down transformer, rectifier, voltage
regulator, and filter circuit for generation of 5v DC power. Here a brief description of all the
components are given as follows:
4.2 TRANSFORMER:
Transformer is a device that transfers electrical energy from one circuit to another through
inductively coupled conductors —the transformer's coils or "windings". Except for air-core
transformers, the conductors are commonly wound around a single iron-rich core, or around
separate but magnetically –coupled cores. A varying current in the first or "primary" winding
creates a varying magnetic field in the core (or cores) of the transformer. This varying magnetic
field induces a varying electromotive force (EMF) or "voltage" in the "secondary" winding. This
effect is called mutual induction.
Fig.-4.1 Show the transformer

15. If a load is connected to the secondary circuit, electric charge will flow in the secondary winding
of the transformer and transfer energy from the primary circuit to the load connected in the
secondary circuit.
The secondary induced voltage VS, of an ideal transformer, is scaled from the primary VP by a
factor equal to the ratio of the number of turns of wire in their respective windings:
By appropriate selection of the numbers of turns, a transformer thus allows an alternating voltage
to be stepped up — by making NS more than NP — or stepped down, by making it
BASIC PARTS OF A TRANSFORMER
In its most basic form a transformer consists of:
 A primary coil or winding.
 A secondary coil or winding.
 A core that supports the coils or windings.
Fig. -4.2 primary and secondary windings.
15

16. 4.2.1 THE COMPONENTS OF A TRANSFORMER:-
Two coils of wire (called windings) are wound on some type of core material. In some cases the
coils of wire are wound on a cylindrical or rectangular cardboard form. In effect, the core
material is air and the transformer is called an AIR-CORE TRANSFORMER. Transformers used
at low frequencies, such as 60 hertz and 400 hertz, require a core of low-reluctance magnetic
material, usually iron. This type of transformer is called an IRON-CORE TRANSFORMER.
Most power transformers are of the iron-core type. The principle parts of a transformer and their
functions are:
 The CORE, which provides a path for the magnetic lines of flux.
 The PRIMARY WINDING, which receives energy from the ac source.
 The SECONDARY WINDING, which receives energy from the primary winding and
16
delivers it to the load.
 The ENCLOSURE, which protects the above components from dirt, moisture, and
mechanical damage.
4.3 BRIDGE RECTIFIER:-
A bridge rectifier makes use of four diodes in a bridge arrangement to achieve full-wave
rectification. This is a widely used configuration, both with individual diodes wired as shown
and with single component bridges where the diode bridge is wired internally.
Basic operation
According to the conventional model of current flow originally established by Benjamin Franklin
and still followed by most engineers today, current is assumed to flow through electrical
conductors from the positive to the negative pole. In actuality, free electrons in a conductor
nearly always flow from the negative to the positive pole. In the vast majority of applications,
however, the actual direction of current flow is irrelevant. Therefore, in the discussion below the
conventional model is retained. In the diagrams below, when the input connected to the left
corner of the diamond is positive, and the input connected to the right corner is negative,
current flows from the upper supply terminal to the right along the red (positive) path to the
output, and returns to the lower supply terminal via the blue (negative) path.

17. Fig.-4.3 Show BRIDGE RECTIFIER
In each case, the upper right output remains positive and lower right output negative. Since this
is true whether the input is AC or DC, this circuit not only produces a DC output from an AC
input, it can also provide what is sometimes called "reverse polarity protection". That is, it
permits normal functioning of DC-powered equipment when batteries have been installed
backwards, or when the leads (wires) from a DC power source have been reversed, and protects
the equipment from potential damage caused by reverse polarity.
Prior to availability of integrated electronics, such a bridge rectifier was always constructed from
discrete components. Since about 1950, a single four-terminal component containing the four
diodes connected in the bridge configuration became a standard commercial component and is
now available with various voltage and current ratings.
4.3.1 OUTPUT SMOOTHING:-
For many applications, especially with single phase AC where the full-wave bridge serves to
convert an AC input into a DC output, the addition of a capacitor may be desired because the
bridge alone supplies an output of fixed polarity but continuously varying or "pulsating"
magnitude (see diagram above).
The function of this capacitor, known as a reservoir capacitor (or smoothing capacitor) is to
lessen the variation in (or 'smooth') the rectified AC output voltage waveform from the bridge.
One explanation of 'smoothing' is that the capacitor provides a low impedance path to the AC
component of the output, reducing the AC voltage across, and AC current through, the resistive
load. In less technical terms, any drop in the output voltage and current of the bridge tends to be
17

18. canceled by loss of charge in the capacitor. This charge flows out as additional current through
the load. Thus the change of load current and voltage is reduced relative to what would occur
without the capacitor. Increases of voltage correspondingly store excess charge in the capacitor,
thus moderating the change in output voltage / current.
The simplified circuit shown has a well-deserved reputation for being dangerous, because, in
some applications, the capacitor can retain a lethal charge after the AC power source is removed.
If supplying a dangerous voltage, a practical circuit should include a reliable way to safely
discharge the capacitor. If the normal load cannot be guaranteed to perform this function,
perhaps because it can be disconnected, the circuit should include a bleeder resistor connected as
close as practical across the capacitor. This resistor should consume a current large enough to
discharge the capacitor in a reasonable time, but small enough to minimize unnecessary power
waste.
Because a bleeder sets a minimum current drain, the regulation of the circuit, defined as
percentage voltage change from minimum to maximum load, is improved. However in many
cases the improvement is of insignificant magnitude. The capacitor and the load resistance have
a typical time constant τ = RC where C and R are the capacitance and load resistance
respectively. As long as the load resistor is large enough so that this time constant is much longer
than the time of one ripple cycle, the above configuration will produce a smoothed DC voltage
across the load.
In some designs, a series resistor at the load side of the capacitor is added. The smoothing can
then be improved by adding additional stages of capacitor–resistor pairs, often done only for sub-supplies
to critical high-gain circuits that tend to be sensitive to supply voltage noise.
The idealized waveforms shown above are seen for both voltage and current when the load on
the bridge is resistive. When the load includes a smoothing capacitor, both the voltage and the
current waveforms will be greatly changed. While the voltage is smoothed, as described above,
current will flow through the bridge only during the time when the input voltage is greater than
18

19. the capacitor voltage. For example, if the load draws an average current of n Amps, and the
diodes conduct for 10% of the time, the average diode current during conduction must be 10.
4.4 REGULATOR IC (78XX):-
It is a three pin IC used as a voltage regulator. It converts unregulated DC current into regulated
DC current.
Fig.-4.4 Show REGULATOR IC
Normally we get fixed output by connecting the voltage regulator at the output of the filtered DC
(see in above diagram). It can also be used in circuits to get a low DC voltage from a high DC
voltage (for example we use 7805 to get 5V from 12V). There are two types of voltage regulators
1. fixed voltage regulators (78xx, 79xx)
2. variable voltage regulators(LM317)
VOLTAGE REGULATORS This include 78xx voltage regulators. The most commonly used
ones are 7805 and 7812. 7805 gives fixed 5V DC voltage if input voltage is in (7.5V, 20V).
19

20. 20
4.5 The Capacitor Filter:-
The simple capacitor filter is the most basic type of power supply filter. The application of the
simple capacitor filter is very limited. It is sometimes used on extremely high-voltage, low-current
power supplies for cathode-ray and similar electron tubes, which require very little load
current from the supply. The capacitor filter is also used where the power-supply ripple
frequency is not critical; this frequency can be relatively high. The capacitor (C1) shown in
figure 4-15 is a simple filter connected across the output of the rectifier in parallel with the load.
Fig.-4.5 Show Full-wave rectifier with a capacitor filter
When this filter is used, the RC charge time of the filter capacitor (C1) must be short and the RC
discharge time must be long to eliminate ripple action. In other words, the capacitor must charge
up fast, preferably with no discharge at all. Better filtering also results when the input frequency
is high; therefore, the full-wave rectifier output is easier to filter than that of the half-wave
rectifier because of its higher frequency.
For you to have a better understanding of the effect that filtering has on Eavg, a comparison of a
rectifier circuit with a filter and one without a filter is illustrated in views A and B of figure 4-16.

21. 21
4.5.1 UNFILTERED:-
Fig.-4.6 Half-wave rectifier with and without filtering
4.6 DTMF DECODER:-
Today, most telephone equipment use a DTMF receiver IC. One common DTMF receiver IC is
the Motorola MT8870 that is widely used in electronic communications circuits. The MT8870 is
an 18-pin IC. It is used in telephones and a variety of other applications. When a proper output is
not obtained in projects using this IC, engineers or technicians need to test this IC separately. A
quick testing of this IC could save a lot of time in re-search labs and manufacturing industries of
communication instruments. Here’s a small and handy tester circuit for the DTMF IC. It can be
assembled on a multipurpose PCB with an 18-pin IC base. One can also test the IC on a simple
breadboard.
For optimum working of telephone equipment, the DTMF receiver must be designed to
recognize a valid tone pair greater than 40 ms in duration and to accept successive digit tone-pairs
that are greater than 40 ms apart. However, for other applications like remote controls and
radio communications, the tone duration may differ due to noise considerations. Therefore, by
adding an extra resistor and steering diode the tone duration can be set to different values.

22. The circuit is configured in balanced-line mode. To reject common-mode noise signals, a
balanced differential amplifier input is used. The circuit also provides an excellent bridging
interface across a properly terminated telephone line. Transient protection may be achieved by
splitting the input resistors and inserting ZENER diodes (ZD1 and ZD2) to achieve voltage
clamping. This allows the transient energy to be dissipated in the resistors and diodes, and limits
the voltage that may appear at the inputs. Whenever you press any key on your local telephone
keypad, the delayed steering (Std) output of the IC goes high on receiving the tone-pair, causing
LED5 (connected to pin 15 of IC via resistor R15) to glow. It will be high for a duration de-pending
on the values of capacitor and resistors at pins 16 and 17.
The optional circuit shown within dot-ted line is used for guard time adjustment. The LEDs
connected via resistors R11 to R14 at pins 11 through 14, respectively, indicate the output of the
IC. The tone-pair DTMF (dual-tone multi-frequency) generated by pressing the telephone button
is converted into bi-nary values internally in the IC. The binary values are indicated by glowing
of LEDs at the output pins of the IC. LED1 represents the lowest significant bit (LSB) and LED4
represents the most significant bit (MSB). So, when you dial a number, say, 5, LED1 and LED3
will glow, which is equal to 0101. Similarly, for every other number dialed on your telephone,
the corresponding LEDs will glow. Thus, a non-defective IC should indicate proper bi-nary
values corresponding to the decimal number pressed on your telephone key-pad.
To test the DTMF IC 8870/KT3170, proceed as follows:
 Connect local telephone and the circuit in parallel to the same telephone line.
 Switch on S1. (Switch on auxiliary switch S2 only if keys A, B, C, and D are to be used.)
 Now push key ‘*’ to generate DTMF tone.
 Push any decimal key from the telephone keypad.
 Observe the equivalent binary as shown in the table.
4.7 DIODE:-
The diode is a p-n junction device. Diode is the component used to control the flow of the
current in any one direction. The diode widely works in forward bias.
22

23. Fig.-4.7 Show the diode
Diode When the current flows from the P to N direction. Then it is in forward bias. The Zener
diode is used in reverse bias function i.e. N to P direction. Visually the identification of the
diode`s terminal can be done by identifying he silver/black line. The silver/black line is the
negative terminal (cathode) and the other terminal is the positive terminal (cathode).
APPLICATIONS
•Zener diode: Voltage control, regulator etc.
•Tunnel diode: Control the current flow, snobbier circuit, etc
4.8 RESISTORS:-
The flow of charge through any material encounters an opposing force similar in many respects
to mechanical friction. this opposing force is called resistance of the material .in some electric
circuit resistance is deliberately introduced in form of resistor. Resistor used fall in three
categories , only two of which are color coded which are metal film and carbon film resistor .the
third category is the wire wound type ,where value are generally printed on the vitreous paint
finish of the component. Resistors are in ohms and are represented in Greek letter omega, looks
as an upturned horseshoe. Most electronic circuit require resistors to make them work properly
and it is obliviously important to find out something about the different types of resistors
available. Resistance is measured in ohms, the symbol for ohm is an omega ohm. 1 ohm is quite
small for electronics so resistances are often given in kohm and Mohm. Resistors used in
electronics can have resistances as low as 0.1 ohm or as high as 10 Mohm.
Fig.-4.8 Show the symbol of resistance
23

24. 24
4.8.1TYPES OF RESISTORS:-
FIXED VALUE RESISTORS
It includes two types of resistors as carbon film and metal film .These two types are explained
under
CARBON FILM RESISTORS
During manufacture, at in film of carbon is deposited onto a small ceramic rod. The resistive
coating is spiraled away in an automatic machine until the resistance between there two ends of
the rods is as close as possible to the correct value. Metal leads and end caps are added, the
resistors is covered with an insulating coating and finally painted with colored bands to indicate
the resistor value
Fig.-4.9 Show the Carbon Film Resistors
Another example for a Carbon 22000 Ohms or 22 Kilo-Ohms also known as 22K at 5%
tolerance: Band 1 = Red, 1st digit Band 2 = Red, 2nd digit Band 3 = Orange, 3rd digit, multiply
with zeros, in this case 3 zero's Band 4 = Gold, Tolerance, 5%
METAL FILM RESISTORS:-
Metal film and metal oxides resistors are made in a similar way, but can be made more
accurately to within ±2% or ±1% of their nominal value there are some difference in
performance between these resistor types, but none which affects their use in simple circuit.

25. 25
WIRE WOUND RESISTOR :-
A wire wound resistor is made of metal resistance wire, and because of this, they can be
manufactured to precise values. Also, high wattage resistors can be made by using a thick wire
material. Wire wound resistors cannot be used for high frequency circuits. Coils are used in high
frequency circuit. Wire wound resistors in a ceramic case, strengthened with special cement.
They have very high power rating, from 1 or 2 watts to dozens of watts. These resistors can
become extremely hot when used for high power application, and this must be taken into account
when designing the circuit.
TESTING :-
Resistors are checked with an ohm meter/millimeter. For a defective resistor the ohm-meter
shows infinite high reading.
CAPACITORS:-
In a way, a capacitor is a little like a battery. Although they work in completely different ways,
capacitors and batteries both store electrical energy. If you have read How Batteries Work , then
you know that a battery has two terminals. Inside the battery, chemical reactions produce
electrons on one terminal and absorb electrons at the other terminal.
BASIC
Like a battery, a capacitor has two terminals. Inside the capacitor, the terminals connect to two
metal plates separated by a dielectric. The dielectric can be air, paper, plastic or anything else
that does not conduct electricity and keeps the plates from touching each other. You can easily
make a capacitor from two pieces of aluminum foil and a piece of paper. It won't be a
particularly good capacitor in terms of its storage capacity, but it will work. In an electronic
circuit, a capacitor is shown like this:

26. Fig.-4.10 Show the Capacitor
When you connect a capacitor to a battery, here’s what happens:
•The plate on the capacitor that attaches to the negative terminal of the battery accepts electrons
that the battery is producing.
•The plate on the capacitor that attaches to the positive terminal of the battery loses electrons to
the battery.
Fig.- 4.11 Show the capacitor &battery connection
4.9 LED:
LED falls within the family of P-N junction devices. The light emitting diode (LED) is a diode
that will give off visible light when it is energized. In any forward biased P-N junction there is,
26

27. with in the structure and primarily close to the junction, a recombination of hole and electrons.
This recombination requires that the energy possessed by the unbound free electron be
transferred to another state. The process of giving off light by applying an electrical source is
called electroluminescence.
Fig.-4.12 LED & Its SYMBOL
LED is a component used for indication. All the functions being carried out are displayed by
led. The LED is diode which glows when the current is being flown through it in forward
bias condition. The LEDs are available in the round shell and also in the flat shells. The
positive leg is longer than negative leg. Function LEDs emit light when an electric current
passes through them. Connecting and soldering LEDs must be connected the correct way
round, the diagram may be labelled a or + for anode and k or - for cathode (yes, it really is k,
not c ,for cathode!). The cathode is the short lead and there may be a slight flat on the body
of round LEDs. If you can see inside the LED the cathode is the larger electrode (but this is
not an official identification method).LEDs can be damaged by heat when soldering, but the
risk is small unless you are very slow.
Never connect an LED directly to a battery or power supply! It will be destroyed almost
instantly because too much current will pass through and burn it out. LEDs must have a
resistor in series to limit the current to a safe value, for quick testing purposes a 1k resistor
is suitable for most LEDs if your supply voltage is 12V or less. Remember to connect the
LED the correct way round LEDs are available in red, orange, amber, yellow, green, blue and
white. Blue and white LEDs are much more expensive than the other colours. The colour of
an LED is determined by the semiconductor material, not by the colouring of the 'package'
27

28. (the plastic body). LEDs of all colours are available in uncoloured packages which may be
diffused (milky) or clear (often described as 'water clear'). The coloured packages are also
available as diffused (the standard type) or transparent.
28
4.10 DC MOTOR:-
DC Motor has two leads. It has bidirectional motion
 If we apply +ve to one lead and ground to another motor will rotate in one direction, if
we reverse the connection the motor will rotate in opposite direction.
 If we keep both leads open or both leads ground it will not rotate (but some inertia will be
there).
 If we apply +ve voltage to both leads then braking will occurs.
Fig.-4.13 Show the dc moter
Electric motors represent an important fraction of residential, commercial, and industrial loads;
in the neighborhood of 60% of the electric energy in the United States is consumed by motors of
some kind. Motor loads comprise fans, pumps of all kinds including refrigerators and air
conditioners, power tools from hand drill to lawn mower, and even electric streetcars—basically,
anything electric that moves.
A motor is essentially the same thing as a generator operated backwards; electrical and
mechanical energy are converted into one another by means of a magnetic field that interacts

29. with both the rotating part of the machine and the electrons inside the conductor windings. The
mechanical power output of a motor is conventionally expressed in units of horsepower(hp),
where 1 hp¼0.746 kW, to distinguish it from the electrical power expressed in kilowatts.
29
4.11 μ VISION:-
The μ Vision IDE is, for most developers, the easiest way to create embedded system programs.
This chapter describes commonly used μ Vision features and explains how to use them. General
Remarks and Concepts Before we start to describe how to use μVision, some general remarks,
common to many screens1 and to the behavior of the development tool, are presented. In our
continuous effort to deliver best-in-class development tools, supporting you in your daily work,
μVision has been built to resemble the look-and-feel of widespread applications. This approach
decreases your learning curve, such that you may start to work with μ Vision right away.
μ Vision windows can be re-arranged, tiled, and attached to other screen areas or windows
respectively It is possible to drag and drop windows, objects, and variables A Context Menu,
invoked through the right mouse button, is provided for most objects. You can use keyboard
shortcuts and define your own shortcuts. You can use the abundant features of a modern editor.
Menu items and Toolbar buttons are greyed out when not available in the Current context.
Graphical symbols are used to resemble options, to mark unsaved changes, or reveal objects not
included into the project. Status Bars display context-driven information. You can associate
μVision to third-party tools
Procedure to Program a Chip
 Connect the PRO51 to COM port and USB port on your PC. USB is used for +5V power
supply only. You can use regulated 5V supply and connect it on pin 4 of the 9 Pin
connector.
 Start PROG51 from your program menu.
 Select appropriate com port on your PC.

30.  Insert desired device in the ZIF socket on PRO51. 20 Pin devices like 89C2051 should
be aligned with the boll tom side, i.e., pin 10 on the 89C2051 should be inserted in Pin 20
of the socket.
 Specify the device in the target device text box.
 Click Identify button to check if the device inserted matches with the one you specified
30
in the Target Device text box.
 Load Hex or Binary file generated using compiler or assembler in the buffer.
 Click on Erase button to erase the contents of the flash memory of the microcontroller.
Erase process will automatically be followed by a blank check.
 Click on Program button to write the buffer contents in to the program memory of the
microcontroller. Program action will automatically be followed by a verify cycle.
 If you wish click on Lock button to secure the device.
 Remove the device from ZIF socket.
COMPONENTS PRECAUTIONS:
 IR sensor used should be sensitive. Before using in the circuit it should be tested with a
multi-meter.
 I.C should not be heated much while soldering; too much heat can destroy the I.C. For
safety and ease of replacement, the use of I.C socket is suggested.
 While placing the I.C pin no 1 should be made sure at right hole.
 Opposite polarity of battery can destroy I.C so please check the polarity before switching
ON the circuit. One should use diode in series with switch for safety since diode allows
flowing current in one direction only.
 Each component was soldered neatly and clean.
 We should use insulated wires.

31. 31
4.12 SOLDERING INSTRUCTIONS:-
Ensure that parts to be soldered and the PCB are clean and free from dirt or grease. Use
isopropyl alcohol with the help of non-static bristol brush for cleaning. Use lint-free muslin cloth
for wiping or alternatively use mild soap solution followed by thorough rinsing with water and
drying.
Tips for good Soldering: Use 15 to 25 watt soldering iron for general work involving small
joints and for CMOS IC’s, FETS and ASIC’S use temprature controlled soldering station
ensuring that the tip temperature is maintained within 330-350 deg. centigrade. For bigger joints
use elevated temperature as per job. Before using a new tip, ensure that it is tinned and before
applying the tip to the job, wipe it using a wet sponge. Use 60 : 40 (tin : lead) resin core (18-20
SWG) solder. Ensure that while applying the tip to the job, the tip of the soldering iron is held at
an angle such that the tip grazes the surface to be heated and ensure that it does not transfer heat
to other joints/components in its vicinity at the same time heating all parts of joint equally. Heat
the joint for just the. right amount of time, during which a short length of solder flows over the
joint and then smoothly withdraw the tip. Do not carry molten solder to the joint. Do not heat the
electronic parts for more than 2-4 seconds since most of them are sensitive to heat. Apply one to
three mm solder which is neither too less nor too much and adequate for a normal joint. Do not
move the components until the molten solder, at the joint has cooled.
Tips for de-soldering: Remove and re-make if a solder joint is bad or dry. Use a de-soldering
pump which is first cocked and then the join tis heated in the same way as during soldering, and
when the solder melts, push the release button to disengage the pump. Repeat the above
operation 2-3 times until the soldered component can be comfortably removed using tweezers or
long no sepliers. Deposit additional solder before using the de-soldering pump for sucking it in
case of difficulty in sucking the solder if it is too sparse as this will hasten the de-soldering
operation.
Alternatively, use the wet de-soldering wick using soldering flux which is nothing but a fine
copper braid used as a shield in coaxial cables etc. and then press a short length of the wick using
the tip of the hot iron against the joint to be de soldered so that the iron melts the solder which is
drawn into the braid.

32. CONCLUSION
In the process of realizing this project, the construction was initially carried out on a breadboard
to allow for checking and to ascertain that it is functioning effectively. All irregularities were
checked then tested and found to have a satisfactory output. The component were then removed
and transferred to a Vero board strip and soldered into place and all discontinuous point were cut
out to avoid short-circuiting.
So far the present system is designed mainly for the supervision applications. In the area of
suspectance, the robot can be directed and if any smoke or gas is identified the robot can produce
alarm and also informs the operator.
The comments from the operator can also be transmitted to the area where the robot moves.
Further the key board can be interfaced with the TV connected at receiver side to increase the
number of comments given to the robot.
Amplifier is needed to be connected to the speaker of the mobile interfaced with the robot to
pass the comments directly through mobile from the remote mobile. The above system can also
used for military purpose as bomb detection and as spy robot.
The construction was carried out with care. The precautions taken during the soldering were:
 The tip of soldering iron was kept clean with the help of a file from time to time.
 The solder wire was of smaller thickness.
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33. REFERENCES
1. “8051 and embedded system” by Mazidi and Mazidi
2. All datasheets from www.datasheetcatalog.com
3. About AT89s8252 from www.atmel.com And www.triindia.co.in
4. http://www.scribd.com/doc/13283625/understanding-switched-capacitor-analog-blocks#
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fullscreen:on
5. http://focus.ti.com/lit/an/sloa093/sloa093.pdf
6. http://www.scribd.com/doc/36463383/7/DTMF-DUAL-TONE-MULTI-FREQUENCY
7. http://www.dnatechindia.com/index.php/Tutorials/8051-Tutorial/Interfacing-8870-
DTMF-DECODER.html
8. http://www.swrtec.de/swrtec/clinux/avrgcc/UOP_ATMega_Handbook_1_0.pdf

34. Appendix
List of Figures
Fig name page no
Fig.-1.1 Show the block diagram of controlling robot using DTMF. (2)
Fig.-1.2 Dual Tone Multi Frequency (DTMF) Frequency Standards (3)
Fig.-1.3 Show the pin diagram DTMF DECODER (4)
Fig.-2.1 Show the TEST CIRCUIT (5)
Fig.-2.2 Pin diagram ATMEGA-16 micro controller in our circuit to control the robot (7)
Fig.-2.3 Controll DC motors with an H-Bridge IC (8)
Fig.-2.4 Mobile phone is connected to ear phones (8)
Fig.-2.5 Show the different IC in Robot System (9)
Fig.-3.1 An entire computer on single chip (12)
Fig.-3.2 pin diagram of the 8051 (13)
Fig.-4.1 Show the transformer (14)
Fig.-4.2 Primary and Secondary Windings. (15)
Fig.-4.3 Show BRIDGE RECTIFIER (16)
Fig.-4.4 Show REGULATOR IC (18)
Fig.-4.5 Show Full-wave rectifier with a capacitor filter (19)
Fig.-4.6 Half-wave rectifier with and without filtering (19)
Fig .-4.7 Show the diode (21)
Fig.-4.8 Show the symbol of resistance (21)
Fig.-4.9 Show the Carbon Film Resistors (22)
Fig.-4.10 Show the Capacitor (23)
Fig.-4.11 Show the capacitor &battery connection (23)
Fig.-4.12 LED &Its SYMBOL (24)
Fig.-4.13 Show the dc moter (25)
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35. Appendix B:
List of Tables
Table name page no.
Table- 2.1 outputs produced by the DTMF decoder (6)
Table -2.2 The following table gives you the logic to drive the dc motors. (7)
Appendix C:
Abbreviations
DTMF - Dual Tone Multi Frequency
LED - light emitting diode
SP - stack pointer
PSW - program status word
DPTR - data pointer
ROM - Read Only Memory
RAM - Read Access Memory
PKV - Public Key Validity
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